marsh



T. A. MARSH.

FURNACE STOKER.

APPLICATION FILED FEB.IG,1911.

Patented June 3, 1919.

3 SHEETS-SHEET l' Q JWNMNKM. H Q m,

www.

l Uvfwrll I HHN ...nl

@in E um.

K n qu 1 1 1.1: ..11

nur

JNN.

T. A. MARSH.

FURNACE STOKER. APPLICATION F-xLED FEB. le, 19u.

Patented June 3, 1919.

3 SHEETS-SHEET 2.

m: y i

w 1l-- s .sl/ +1 4/" .l X QQ faz/72x57? T. A. MARSH.

FURNACE STOKER.

APPLICATION man FE.1s,1917.

Patented June 3, 1919.

UNITED stares raannr ernten.

THOMAS A. MARSH, 0F CHICAGO, ILLINOIS, ASSIG-NR T0 GREEN ENGINEERING COMPANY, OF EAST CHICAGO, INDIANA, CORPORATION 0F ILLINOIS.

rumanos-stroken;

Specication of Letters Patent.

Patented June 3, 1919.

Application led February 16, 1917. Serial No. 148,926.

' To all whom t may concern.'

This invention relates to improvements inl furnace stokers, and more particularly to a construction for mechanical stokers of the underfced type, adapted for use with steam boilers of commercial design, the stoker-` embracing as its main elements a grate of the progressive feed type, such as an endless or travelin chain grate, and fuel retorts or receptac es, into which the fuel is fed `by suitable plunger mechanism, and from thence forced upwardlyinto the fuel bed, in accordance with the underfeed principle of stokers.

A preferable construction for a furnace and Stoker embodying the features of the invention, is illustrated in the accompanying drawings, whereini Figure l is a view in longitudinal section taken through the forward portion of the furnace and the stoker embodying the features of the invention, and taken on line 1-1 of Fig. 2;

Fig. 2 is a view in cross-section of the Stoker, taken on line 2 2 of Fig. 1;

Fig. 3 is a fragmentary plan view of the rear portion of the chain grate;

Fig. 4 is an enlarged detail view in crosssection of a fuel retort;

Fig. 5 is an enlarged fragmentary plan view of a retort, showing twyer blocks along one side of the retort, removed; and Fig. 6 is an enlarged detail view in longitudinal section of the front portion of a retort and adjacent parts.

The objects of the invention are directed to providing a practical and eiicient stoker, involving the adaptation of the underfeed principle of stoking lto the well-known traveling chain grate, and to certain novel details of construction, making possible of accomplishment the general purpose in view, as well as providing for asuitable supporting structure for the Stoker elements and air supply or draft to thegrate surface, all of which is herein fully described' and illustrated.

,A Stoker' of the type to which my invencombustion chamber.

tion relates is adapted for use in steam boiler furnaces of any well-known or standard construction and herein illustrated as comprising side walls l0, 10, a front wall 11, and top and rear walls (not shown), all being of brick construction, common to furnacesl of this type.' Within the forward' part of thefurnace is formed the combustion chamber, extending rearwardly from the front wall 11 to a cross-wall 12, intermediate the front and rear walls. Mounted in the space above the'combustion chamber is a water tube boiler 13, of well-known construction, embracing longitudinally extending tubes 14 connected at their forward ends to a front header 15 supported adjacent the front wall 11 and above a cokin breast 16, overhanging the forward portion of the The tubes extend rearwardly yfrom the frontheader 15 to a similar rear header mountedv in the back portion of the furnace, said tubes being further supported-intermediate their ends upon the cross-wall 12.

Within the combustion chamber is located the grate 17, the same being of the endless chain type, as heretofore mentioned, constructed of a multitude of short links 17El joined together so as to form a flexible chain or grate surface. The grate consists of two lorizoutal and parallel portions or leads 18 and 19, the upper portion 18 forming the active grate surface, and the lower or return portion 19 being spaced a distance below the upper portion. The grate is s upyin vertical position and spaced apartfin equidistant relation throughout the length of the grate, there being shown (Fig. 1) four of such beams, the outermost beams 21 being spaced inwardly from the ends of the grate. The side frame members 2O and cross-beams 21l form a rigid frame Structure, carrying the chain grate supporting elements as follows: At the forward and rear ends of the grate are transverse shafts 22, 22, upon which are keyed a plurality of sprocket wheels 23, which mesh with and carry the ends of the chain grate 17, the

shafts 22 being journaled at their ends within bearings 24 mounted upon an integral flange 25 extending along the upper margins of the side frame members 20. The forward sprocket shaft 22 and wheel 23 are supported exteriorly of the front wall l1 of the furnace by means of suitable bearings, there being connected with said forward sprocket shaft 22 actuating mechanism for rotating said shaft 22 and imparting Inovement to the grate 17 in a direction to advance the upper or active grate surface from front to rear.

ln addition to the sprocket shafts and wheels, the grate is supported by means of rollers 26 and 27, mounted below the upper and lower grate portions, respectively, and intermediate the ends of the grate, the rollers 26 being journaled in bearings 28 mounted upon the flanges 25 of the side frame members 20 and upon the upper anges of the cross-beams 2l, and the rollers 27 journaled in bearings 29 mounted below the cross-beams. As will hereinafter appear in connection with the description of the retorts and arrangement of the draft ducts, the rollers are arranged in sets, each comprising separate rollers, spaced apart at their ends and having separate bearings.

Associated with the chain grate and constituting the underfeeding element of the stoker, are two horizontal and parallel fuel receptacles yor retorts 30, 30, which extend inwardly from the forward end of the furnace and throughout a portion of thelength of the grate. In order to provide longitudinal spaces or openings for the retorts, the chain grate is preferably divided into strands, which are spaced. apart, thereby forming between the margins thereof openings or spaces extending throughout thelength of the grate. The retorts project from the forward end of the furnace into said spaces and beneath the. upper portion or active grate surface, the upwardly facingopeniug or mouth of each retort being flush with or lying in the plane of said active grate surface and the margins thereof in close proximity to the edges of the strands. As a preferable arrangement, the openings between the strands, which define the positions of the retorts, are spaced equal distances inwardly from the side walls of the furnace, such distances being substantially equal to one-half the distance between the retorts. In this manner the grate is divided into three strands of chain, to wit,

a central strand 31 extending between the retorts and two outer strands 32, 32 between the retorts and the side walls, the central strand beingl 'substantiall twice the width of the outer strands. us the grate is necesites divided into two units, each consisting of a retort 30, an outer strand 32, and the adjacent one-half of the central strand 31.

The retorts 30, 30 are trough-like metal receptacles substantially U-shaped in crosssection (Fig. 4t), having outwardly inclined or flaring side walls 30o, 3()a extending upwardly from a rounded bottom wall 30". The front end 30c `of veach retort 30 projects beyond the' front wall 11 of the furnace, and the rear end 30 terminates short of' the adjacent rearend of the grate 17 in a rearwardly and upwardly inclined wall 33. The retorts being duplicates of each other in structure and the method of supporting the same being identical, the following detailed description of one retort or unit will suffice for both. Extending along the upper longitudinal margins of the retort are rows of twyer blocks 34 (Figs. l and 5), lying 85 adjacent to the edges of the grate and forming a marginal lining for the retort, said blocks being constructed of fire-clay -or like fire-resisting material, and provided with air passages or twyers 35 therethrough, ex-A tending from their under surface upwardly and inwardly, the twyer openings being arranged4 along the inner surface ofv theretort, 'a short distance below the edge thereof. rlfhe use of twyer blocks, as is the common practice, prevents the burning out of portions of the retorts subjected to the higher temperature of the fuel bed, whereas the air passages or twyers serve to deliver air from the draft ductsbeneath the grate 100 directly t0 the fuel at the mouth of the retort. .The twyer blocks 34 are preferably mounted upon laterally projecting integral flanges 36, 36 along the side margins of the retort proper, said flanges having elongated rectangular openings 37 therein. Upon the under side of the twyer blocks 3i are formed similarly shaped project-ing portions 38, adapted to register with and fit within said openings, thus supporting and 110 retaining theblocks in place, as well as providing for the passage of air through the twyers 35 from the space below the grate. The retorts extend downwardly below the upper portion of the grate, and, in 115 order to provide space therefor, portions of the transverse cross-beams 21 are cut away, adjacent the upper margins thereof, thus forming a U-shaped yoke 21a conforming to the outer surface of the retorts. It is vbe- 120 cause of the presence of the retorts beneath the grate surface and the division of the chain grate into separate strands, that sets of rollers 26 are mounted upon each crossbeam, each roller supporting'ja strand of the 125 chain. So, also, separate bearings 28 for each roller are employed, those adjacent to the retorts being mounted in close proxiinity thereto and upon the flanges of said cross-beams.

Each of the retorts is supported upon a series of vertical girders 39, 39, arranged end to end and extending longitudinally throughout the length of the grate, each girder extending transversely between each pair of adjacent cross-beams and downwardly from the under surface of each re-` tort and resting. upon the surface of the bottom wall 40 of the furnace setting. The irders are provided with upper marginal anges 4l, upon which thelattened bottom surface of the retort rests, said flanges being preferably U-shaped in sectional contour, thereby providing just below the retort a longitudinal channel, for a purpose hereinafter to be set forth. The girders are also provided with lower marginal flanges 42, which serve as feet to support the same upon the bottom wall 40. At the ends of each of the girders' 39 are provided integral flanges 43, extending laterally from opposite sides of each girder, said flanges being preferably reduced or tapered 'at their upper and lower ends, the upper ends abutting flatwise against the cross-beams and securely bolted thereto. In order to permit close contact between the cross-beams 21 and the girderflanges 43, a considerable portion of the lower marginal webs of the cross-beams is removed adjacent the flanges 43 and on either side of said girders. The vertical margins of said flanges of each girder extend outwardly to the margins of the adjacent strands of the chain, and serve to form narrow partition walls, depending from the cross-leams 21, as will hereinafter appear. Exten ing transversely between the crossbeams 21 and between the margins of the flanges 43,443 of each vertical'supporting ygirder are longitudinal partition walls 44 and 45 of sheet metal construction, spaced from and on either side of each girder 39, each of said partition walls comprising a vertical portion extending parallel to and at a distance from the adjacent girder and inclined upper portion located intermediate the leads of the chain grate, and arranged as follows: The partition walls 44, 44 included between each pair of corresponding girders are inclined inwardly toward-each other, meeting at a point or apex immediately below and centrally of the central strand 3l of the grate, thus yforming a complete closure surroundingthel lower portion of the central Strand. On the other hand, the outermost partition walls 45 are inclined upwardly and outwardly, abut-ting at their upper margins against the side walls l0, 10 of the furnace and also inclosing the'parts below. The partition walls are secured to the vertical flanges 43, 43 ofthe supporting girder and to the faces of the cross-beams 2l by means of marginal flanges integral with said walls, and bolts or rivets. The lower edges of the partition walls terminate above the surface of the bottom 'wall 40, there being .provided further partition walls in the form of hor1zontal floor plates 46, spacedk above and parallel to the bottom wall 49. The floor' `walls 44, 45 and the plates 46 being connected together by means of suitable lugs and bolts, as shown. Referring again to the flanges 43, 43 of the girders 39, 39, these members also serve to support the bearings 29 of the lower rollers 27, said bearings being provided with integral plates 47, which lie flatwise against the `flanges and are bolted thereto.

The supporting structure or frame of the Stoker, embracing the transverse cross-beams 21, the longitudinal supporting girders 39 and their flanges 43, together with the partition walls 44, 45 has for its purpose the formation ofa plurality of compartments beneath .the active grate surface, and, furthermore, the formation of vertical air passages and spaces for conducting the air or draft from the air ducts beneath the grate, as will be understood from the following: As has *been heretofore pointed out, the girders 39 divide the space beneath the grate into three longitudinal compartments associated with each strand of the chain, these compartments being further divided into three smaller .compartments by the transverse beams 21 and the flanges 43l of the supportingv girders. Again, each of the smaller compartments is divided, by the partition walls and floor plates 46, into narrow vertical air passages on either side of each girder 39 and which communicate at their upper ends with upwardly divergent air chambers immediately below the surface of the grate and at their lower ends with the longitudinal air ducts below the floor plates 46. In this manner air under pressure is introduced into the lower air ducts from a suitable source, such` as a blower, and from thence passes upwardly through the vertical air passages into the air chambers beneath the strands of the chain grate, the air being thus forced into the fuel bed through the so that by the 'introduction of suitable dampers (not shown) in connection with the longitudinal airducts as well as several Vvertical air passages, it is possible to control the delivery of air to each air area of grate surface, and thus obtain accurate control of -the draft and operating conditions of the retorts, a plurality of auxiliary strands of chain 50 Figs. 1 and 3) are employed, said strands having a width equal to the width of the openings betweeny the strands and extending from the rear ends of the retorts to the rear end of the grate. These short or auxiliary strands of chain are supported at their rearmost ends upon sprocket wheels 51, mounted upon the rear sprocket shaft 22 and identical in all respects to the rear sprocket wheels-23 carrying the main strands of the chain." The forwa'rd ends of the auxiliary strands 50 are carried by auxiliary sprocket wheel and shaft mechanism located adjacent to the rear ends of the retorts and comprising a shaft 52 journaled at its ends in bearings 53 supported upon the side frame members 20, in the same manner as are the bearings 24, 24 of the main rear sha-ft 22. Mounted on the shaft 52 are a plurality of sprocket wheels 54, which carry the auxiliary strands 50. The auxiliary strands of chain 50 are actuated from the rear sprocket shaft and at the same rate of movement. In order to provide space for the auxiliary strands and sprocket wheels, the rear girders 3'9 are cut away throughout the portions rearwardly ofthe retorts (as shown in Fig. l) along a line extending in close proximity to the surface of the lower portions of said auxiliary strands.

Referring now to the means for introducing fuel into the retorts and for advancing the fuel therein, the following arrangement of elementsv is employed: Communicating with the forward vends of the retorts are fuel hoppers 55, 55, said fuel hoppers being located above the forward ends of the retorts and adjacent to the front wall of the furnace and comprising upwardly opening receptacles having downwardly inclined or tapered side walls terminating at their lower margins in a comparatively small discharge opening immediately above the front ends of the retcrts and in front of the margin of an inclined plate 56, set in the frontwall 1l above the retort and providing a rearwardly flaring mouth or fuel intake opening. Se-

cured to the front end of each retort and extending outwardly in axial alinement therewith, is a cylinder 57, opening endwise into the retort at a point just forward of the` discharge opening of the fuel hopper. lVithin the cylinder 57 is mounted an endwise moving piston or plunger 58, adaptedvanced along the retort.

A desirable mechanism for operating the plungers comprises the following arrangement of elements: Immediately forward of each plunger cylinder 57 and mounted upon the floor in front of the furnace, is an upright stand or bracket 59,'having at its upper end a bearing 60, supporting a horizontal shaft 61, carrying at one end a. worm 62 and at its opposite end a worm wheelV 63. Immediately above the worm 62 and extending transversely of the shaft 61, is a crank-shaft 64 provided with a worm wheel 65 in driving engagement with the worm 62fand having a crank 66 opposite each of the retorts and connected to each plunger by means of a connecting rod 67 by the usual form of journal and wrist-pin connections. Extending transversely of the worm shaft 6l and immediately below the worm wheel 63 mounted thereon, is a drive-shaft 68, having a worm 69 mounted thereon and having engagement with said worm wheel 63, said shaftbeing journaled ina suitable yoke or bearing 70 integral with the bracket 59, the

Vlatter being further providedwith an eX- tension 71 in axial alinement with the worm shaft bearing 60 and rigidly connected to the forward end of the cylinder 57, thereby securing a. greater degree of rigidity between the elementsof the Stoker and the driving mechanism. It is obvious that power is transmitted to the plungers from the drive shaft 68 through the medium of the pairs of worm elements and the crank 66 and connecting rod 67, all of these elements being well known expedients Vfor producing reciprocating movement. Furthermore, means may be employed in connection with the actuating mechanism for varying the speed of movement of the plunger,' as well as the length of the stroke thereof, such devices being also well known in the art.

In view of the length'` of the retorts, it "is desirable to provide auxiliary means for advancing the fuel throughout the portions of the retorts within the furnace, and for this purpose a plurality of pushers, in the form of endwise sliding blocks 72, are employed,

.having the form of elongated members provided with a dat vertical front face and a rearwardly inclined top surface to-provide a comparatively narrow rear endor surface,

the purpose of forming the pusher blocks inv this manner being to permit the fuel to be actuated by the blocks When the same are'k moved forwardly, and at the same time allow the blocks to be moved in the opposite direction without disturbing the fuel Within the retort, The pusher blocks 72, shown as two in number, are spacedl at suitable distances apart throughout the' length of the retort, and rest upon and have sliding engagement with the bottom surface thereof, t-here being provided upon their under surface downwardly projecting pins 73, Which extend through slots 7l extending longitudinally of the retorts and formed in the bottom wall thereof. under surface of the retort and located within the U-shaped channel 41 formed along the upper edge of the girders 39, is a' rod 7 5, having rigid connection with the pusher blocks 7 2 by means of the pins 7 3 and suitable connecting members 76. The forward end of the rod 75 terminates adjacent to the forward end of the retorts, and is connected to the plunger 58 by means of a downwardly depending pin 77, rigidly secured to the plunger and projecting through a slot 7 8 in the bottom wall of the retort, and a connect-ing member 79 joining the rod and pin 77. As a preferable construction, the plunger is provided with a projecting lip 80 adjacent to the bottom surface of the retort and serving to cover the slot. 78 in all positions fthe plunger and thus prevent fuel from t ropping through the slot.

The operation of a stoker embodying the features of the invention, as is apparent from the foregoing description, is entirely automatic, the fuel being fed by gravity from the hoppers into the forward end of the retorts, where it is forced or pushed i-nto the furnace by means of the reciprocating plungers (operating continuously or intermittently, as desired). By the act-ion o f the plungers, the fuel is advanced throughout the length of said retorts with the aid of the pusher blocks and beneath the incandescent fuel bed, carried upon the continuously moving grate. The continued feeding of the fuel into the retort forces the fuel therefrom upwardfly into the combustion zone and ignited, whereupon the fuel is gradually carried rearwardly upon the' intermediate strands of chain, in the manner common to chain grate stokers.

l claim as my invention:

l. lu a furnace, in con'ibination, an endless chain grate extending into the furnace and having the upper lap thereof forming the fuel supporting portion of said grate, a fuel retort located beneath the upper portion of said grate and having an opening permitting fuel to be discharged from said re- Immediately below ther neath the upper portion of said grate and opening upwardly throughout substantially the entire'length thereof to permit fuel to be discharged from said retort onto the upper surface of said grate, and means for moving fuel into said retort.

y 3. In a furnace, in combination, a fuel retort extending into the furnace, an endless chain grateextending` into said furnace an'd having a section'on each side of said retort and adapted to receive on the upper surface thereof the fuel discharged from said retort, and 'means for moving fuel into said retort.

4. In a furnace, in combination', a fuel retort extending into said furnace'and opening upwardly -throughout substantially the entire length thereof, an endless chain grate extending into said furnace and having a section on each side of said retort and ada-pted to receive on the upper surface thereof the fuel discharged from said retort; the "upper edges of said retort being substantially flush With the upper surface of said grate, and means for moving fuel into said retort.

5. In .a furnace, in combination, a fuel retortextending into the furnace and being substantially U-shaped in cross-section, an endless chain grate extending into said furnace and having a section on each side of said retort and adapted to receive on the upper surface thereof the fuel discharged from said retort, twyer blocks mounted on said retort along the upper side edges therej of with the upper edges of said blocks substantially fiush with the upper surface of said grate,`and means for moving fuel into said retort.

6. In a furnace, in combination, a fuel retort extending into the furnace and being substantially U-shaped in cross-section, an endless chaingrate extending into said furnace and having a Section on each side of said retort and adapted to receive on the upper surface thereof the fuel discharged from said retort, said retort having outwardly extending flanges along the upper side margins thereof, twyer blocks mounted on said anges with the upper edges of said blocks substantially iush with the upper surface of said grate, means for moving fuel into said4 retort., and said blocks and flanges being provided with registering air ducts.

7. In a furnace, in combination, a retort extending into the furnace and being substantially U-shaped in cross-section, an endless chain grate extending into said furnace and having a section on each side of said retort and` adapted to receive on the upper surface' thereof the fuel discharged from saidretort, a fuel hopper adjacent one end of said retort and opening downward into the saine, a reciprocating plunger in said retort at said hopper, a plurality of pusher blocks located in said retort beyond said plunger, means connecting said pusherl blocks with said plunger, and means for reciprocatingsaid plunger.

8. In a furnace, in combination, a retort extending into the furnace and being substantially U-shaped in cross-section, an endless chain grate extending into said furnace and having a section oneach side of said retort and adapted to receive on the upper surface thereof the fuel discharged from said retort, a fuel hopper adjacent one end of said retort and opening downward into the same, a reciprocating plunger in said retort at said hopper, a plurality of pusher blocks located in said retort` beyond said plunger, an endwise movable rod extending longitudinally of said retort and having connection with said plunger and said pusher blocks, and means for reciprocating' said plunger.

9. In a furnace, in combination, a retort extending into the furnace and being substantially U-shaped in cross-section, an endless chain grate extending into said furnace and having a section on each side of said retort and adapted to receive on the upper surface thereof the fuel discharged from said retort, a fuel hopper adjacent one end of -said retort and opening downward into the same, a reciprocating plunger in said retort at said hopper, a plurality of pusher blocks located in, said retort beyond said lunger, an endwise movable rod extending ongitudinally of said retort below the bottom wall thereof, said retort having elongated slots in its bottom wall, pins extending downward through said slots and connecting said plunger and pusher blocks with said rod, and means for reciprocating said plunger.

10. In a furnace, in combination, anv endless chain grate extending into the furnace and having the upper lap thereof forming the fuel supporting portion of said grate, said grate being divided longitudinally into sections laterally spaced apart, a fuel retort located in the space between each two adjacent gratesections and extending lengthwise thereof with the inner end of the retort terminating short of the inner end of the grate, means for moving fuel into said retort and the latter opening upwardly throughout substantially the entire length thereof to permit fuel to be discharged from said retort onto the upper surface of said grate, and said grate being provided with chain grate sections extending beyond the inner end of each retort. v

11. In a furnace, in combination au end less chain grate extending into the furnace and having-the upper lap thereof forming the fuel supporting portion of said grate, said grate being divided longitudinally into sections laterally spaced apart, a fuel retort located in the space between said sections and extending lengthwise thereof with the inner end of the retort terminating short of the inner end of said grate, means for moving fuel into said retort and the latter opening upwardly throughout substantially the entire length'thereof to permit the fuel to be discharged from said 'retort onto the upper surface of said grate, a rotative shaft at each end of'said grate, sprocket wheels on, said shafts, a rotative shaft immediately beyond the inner end of said retort, sprocket wheels on said last named shaft, and a chain grate section trained over said last named sprocket Wheels-and sprocket wheels on the shaft at the inner end of 'said grate.

12. In a furnace, in combination, an endless chain grate extending into the furnace and having the upper lap thereof forming the fuel supporting portion of said grate,

' said grate being divided longitudinally into sections laterally spaced apart, a fuel retort located in the space between said sections and opening upwardly throughout substantially the entire length thereof so as to permit fuel to be discharged from said retort onto the upper surface of said grate, means for moving fuel into the retort, and a vertical girder extending longitudinally of the grate beneath each retort and upon which the latter rests.

In testimony that I claim the foregoing as my -invention,`I affix my signature in the presence of two witnesses, this 13th day of February, A. D. 1917.

. THOMAS A. MARSH. Witnesses:

INMAN Fommnnnne,

A. S. BRADY. 

